Field
The present specification teaches a protocol for pain management including a pharmaceutical composition and its use in ameliorating the sensation of pain.
Description of Related Art
Bibliographic details of the publications referred to by author in this specification are collected alphabetically at the end of the description.
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.
Pain is a debilitating stimulus. The term “pain” covers a spectrum of stimuli including neuropathic, nociceptive, phantom, psychogenic, breakthrough, incident and asymbolia and insensitivity pain.
Pain is a sensory experience associated with actual or potential tissue damage. Pain of any type is the most frequent reason for physician consultation in the United States, prompting half of all Americans to seek medical care annually. It is a major symptom in many medical conditions, significantly interfering with a person's quality of life and general functioning. Diagnosis is based on characterizing pain in various ways, according to duration, intensity, type (dull, burning or stabbing), source or location in body. Acute pain generally stops without treatment or responds to simple measures such as resting or taking an analgesic. However, if it persists and becomes intractable it then becomes chronic pain, in which pain is no longer considered a symptom but an illness by itself.
Of the different pain types, the management of nociceptive and neuropathic pain has been difficult. Stimulation of a nociceptor due to a chemical, thermal or mechanical event that has the potential to damage body tissue leads to nociceptive pain. Damage to a pain nerve itself leads to neuropathic pain.
Although there are numerous therapies available for nociceptor-induced pain, such as treatment with opioid and non-steroidal anti-inflammatory drugs (NSAIDs), these therapies are often unsatisfactory when administration is required over extended time frames due to the emergence of tolerance and adverse side-effects. For example, common side effects of treatment with opioids include constipation, nausea, sedation, respiratory depression, mycolonus, urinary retention, confusion, hallucinations and dizziness. In addition, extended administration typically leads to drug tolerance, resulting in the need for increased levels of drugs to be administered, thereby further exacerbating the side effects of the drugs.
In addition, treatment of neuropathic pain has not met with particular success. This is due to the distinct pathophysiochemical mechanisms and clinical manifestations associated with neuropathic pain relative to pain caused as a result of nociceptor stimulation. Agents useful in the treatment of pain caused as a result of nociceptor stimulation have reduced effectiveness in neuropathic pain treatment. In particular, the effectiveness of opioids in the treatment of neuropathic pain is diminished relative to their use in the treatment of pain caused as a result of nociceptor stimulation. In particular, drug dose response curves for treatment of neuropathic pain are shifted to the right of those for treatment of pain caused as a result of nociceptor stimulation or acute pain.
Accordingly, there is a need to develop safe and efficacious therapies for the short and long term treatment of pain.